Isomers may have different properties depending on the steric configurations thereof, and the effects thereof may become significantly different if there is a pharmacological function. Hence, a chiral compound is typically used in a manner in which it is separated into pure isomer compounds, and thus it is necessary to develop a technique for separating a chiral compound into optically pure isomers.
β-2-thienyl-alanine is a chiral compound having asymmetric carbon (chiral center) as represented by Chemical Formula 4 below.

β-2-thienyl-L-alanine is an ingredient that is essentially used in the production of medicaments such as icatibant for the treatment of hereditary angioedema and labradimil for increasing the permeability of the blood-brain barrier.
The preparation of optically active β-2-thienyl-alanine using a chiral hydrogenation catalyst (Tetrahedron Asymmetry, 4, 1833(1993)) has been disclosed in the conventional art, but is problematic because an expensive chiral hydrogenation catalyst and high-pressure hydrogen gas have to be used.
Also, the preparation of β-2-thienyl-alanine through a biological reaction using microorganisms or enzymes is known. For example, preparation through an amination reaction of 2-hydroxy-3-thienyl acrylic acid (Tetrahedron Asymmetry, 8, 527(1997) and U.S. Pat. No. 5,688,672 (1997)), preparation through an amination reaction of 3-thienyl acrylic acid (Chemistry—A European Journal, 12, 2739 (2006)), and preparation through another amination reaction (The Journal of Organic Chemistry, 74, 6953 (2009)) are known. However, these methods are disadvantageous because of using enzymes or microorganisms that are difficult to handle upon mass production, and thus industrial applications thereof are limited.